1. Field of the Invention
The present invention relates to power hand tools and, in particular, to pneumatic hand tools and the channeling of air therethrough.
2. Description of the Prior Art
Pneumatic hand tools, such as air ratchets, are well known. Typically, these hand tools have an elongated housing with a handle portion at one end and a head portion at the opposite end carrying a ratchet mechanism. An air motor is typically disposed in the housing intermediate the ends for driving the ratchet mechanism, the air motor being coupled to a source of pressurized air through an air inlet passage which commonly extends axially through the handle portion. The housing may be provided with a trigger, which may be in the form of a lever alongside the outside of the housing or a radially projecting button, adapted to be operated by a finger or fingers of the user's hand which grasps the handle, for operating an internal valve to admit air to the air motor. Typically, the housing and the handle portion thereof are formed of a suitable metal.
In prior air tools, various types of exhaust arrangements have been utilized. In one arrangement the air is exhausted from a forward portion of the housing, sometimes through a muffler arrangement. Commonly, the air exits the air motor into a circumferential passage or chamber which communicates with an exit opening at a forward portion of the housing. Alternatively, rear-exhaust arrangements have also been utilized, which include an exhaust passage which passes back through the handle portion, generally parallel to the inlet passage. While such an arrangement has the advantage of providing more effective cooling of the rear end of the air motor adjacent to the handle portion, it also requires a thicker handle portion to accommodate both the inlet and exhaust passages.